Nasty guy in CIA took one of the order of Hemiptera (6)
I believe the answer is:
cicada
'took one of the order of hemiptera' is the definition.
I can't judge whether this defines the answer.
'nasty guy in cia' is the wordplay.
'nasty guy' becomes 'cad' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'cad' put into 'cia' is 'CICADA'.
Can you help me to learn more?
(Other definitions for cicada that I've seen before include "jumpy creature" , "crawler" , "Droning bug" , "Flier" , "Bug sounding at night" .)